Background/Purpose:

Takayau arteritis (TA) is a large vessel arteritis affecting mainly aorta and its branches. One of the great difficulties to treat TA patients is a lack of reliable criteria to assess disease activity. There is study showing that even in TA patients with no complaints and no abnormal acute phase reactants (classified as inactive disease), at surgical procedure it was found an inflammatory process at vessel wall, characterizing a histologically active disease. The aim of this study was to quantify 18F-fluorodeoxyglucose (FDG) uptake on PET-CT and measure serum levels of IL-2, IL-6, IL-8, IL-12, IL-18, TNF-alfa, MMP-3 and MMP-9 to assess disease activity in TA patients. We also evaluate correlation between FDG uptake on PET-CT and level of these serum biomarker.

Results:

The mean age of patients and controls was respectively 36.2 and 37.0 years and 92% of them were female. The serum level of IL-6 [13.3 pg/ml (95% CI 7.019.6) vs 3.4 pg/ml (95%CI 1.94.8) P<0.001] and of MMP-3 [647.8 pg/ml (95%CI 494.7800.8) vs 563.7pg/ml (95%CI 439.4688.0); P<0.001] were higher in TA patients than in controls. Comparing the serum level of these interleukins and metalloproteinases between patients classified as active vs inactive disease, only IL-6 was significantly higher in patients with active disease (22.5 pg/ml vs 7.5 pg/ml; P=0.027). Regarding SUVmax on PET-CT, patients with active disease had higher SUVmax values than those with inactive disease (P=0.042). ROC curve analysis showed that the value of SUVmax as a predictor of clinical activity (P=0.043; AUC=0.703; IC 95%=0.5340.832). SUVmax >= 1.3 was associated with clinical activity (P=0.039). TNF-alfa levels were higher in patients with SUVmax >= 1.3, when compared to those <1.3 (P=0.045) and to controls (P=0.012). IL-6 and MMP3 levels were higher in patients with SUVmax >= 1.3 than in controls (P<0.001 and P=0.006, respectively). There was no significant difference regarding others serum biomarkers comparing TA patients and controls.

Conclusion:

This is the first study evaluating various interleukins and metalloproteinase to assess disease activity in TA patients. The serum level of IL-6 was associated with disease activity. This study also finds a correlation between 18F-FDG uptake in PET-CT and disease activity. Therefore PET-CT and serum level of IL-6 appear to be promising tools to assess Takayasu arteritis disease activity.